Separated-flow dynamics around a high-speed train with streamline-blunted aerodynamic braking plates under strong crosswinds

This study employs the improved delayed detached eddy simulation method to investigate the effects of streamline-blunted aerodynamic braking plates on the aerodynamic characteristics of a three-car high-speed train under yaw angles of 30° and 45° at Re = 5.0 × 105. The accuracy of the numerical method is validated against the reduced-scale wind tunnel experiments. The results show that the braking plates strengthen local flow separation, shear layer roll up, and flow fluctuations in the upper and leeward-side regions, thereby interrupting the accelerated flow corridor above the train and reorganizing the dominant separated flow on the leeward side. Their influence is concentrated mainly in the head and tail regions, whereas the middle car is affected much less. As the yaw angle increases from 30° to 45°, the global crosswind-induced separation becomes stronger, while the local effect of the braking plates around the head car becomes more diffuse and the corresponding variation in the tail region remains relatively small. The drag enhancement is governed mainly by pressure redistribution over both the plate surfaces and the train body. Specifically, a clear pressure difference is established between the windward and leeward faces of each plate, while the positive pressure in the head car region and the suction in the tail car region are both enhanced. Compared with the original configuration, the drag coefficient of the whole train increases from 0.288 to 1.934 at 30° and from −0.080 to 1.314 at 45°, whereas the changes in lateral force and lift remain limited.